title: Correlation of MRI grading of bone stress injuries with clinical risk factors and return to play: a 5-year prospective study in collegiate track and field athletes.
abstract: BACKGROUND
  Bone stress injuries are common in track and field athletes. Knowledge of risk factors and correlation of these to magnetic resonance imaging (MRI) grading could be helpful in determining recovery time.
  
  
  OBJECTIVE
  To examine the relationships between MRI grading of bone stress injuries with clinical risk factors and time to return to sport in collegiate track and field athletes.
  
  
  METHODS
  Cohort study (prognosis); Level of evidence, 2.
  
  
  METHODS
  A total of 211 male and female collegiate track and field and cross-country athletes were followed prospectively through their competitive seasons. All athletes had preparticipation history, physical examination, and anthropometric measurements obtained annually. An additional questionnaire was completed regarding nutritional behaviors, menstrual patterns, and prior injuries, as well as a 3-day diet record. Dual-energy X-ray absorptiometry was performed at baseline and each year of participation in the study. Athletes with clinical evidence of bone stress injuries had plain radiographs. If radiograph findings were negative, MRI was performed. Bone stress injuries were evaluated by 2 independent radiologists utilizing an MRI grading system. The MRI grading and risk factors were evaluated to identify predictors of time to return to sport.
  
  
  RESULTS
  Thirty-four of the athletes (12 men, 22 women) sustained 61 bone stress injuries during the 5-year study period. The mean prospective assessment for participants was 2.7 years. In the multiple regression model, MRI grade and total-body bone mineral density (BMD) emerged as significant and independent predictors of time to return to sport. Specifically, the higher the MRI grade (P = .004) and lower the BMD (P = .030), the longer the recovery time. Location of the bone injury at predominantly trabecular sites of the femoral neck, pubic bone, and sacrum was also associated with a prolonged time to return to sport. Female athletes with oligomenorrhea and amenorrhea had bone stress injuries of higher MRI grades compared with eumenorrheic athletes (P = .009).
  
  
  CONCLUSIONS
  Higher MRI grade, lower BMD, and skeletal sites of predominant trabecular bone structures were associated with a delayed recovery of bone stress injuries in track and field athletes. Knowledge of these risk factors, as well as nutritional and menstrual factors, can be clinically useful in determining injury severity and time to return to sport.
authors.affiliation: yDepartment of Family Medicine, Division of Sports Medicine, David Geffen School of Medicine at UCLA, University of California, Los Angeles, Los Angeles, California, USA. anattiv@mednet.ucla.edu
authors.forename: Aurelia
authors.initials: A
authors.lastname: Nattiv
authors.forename: Gannon
authors.initials: G
authors.lastname: Kennedy
authors.forename: Michelle T
authors.initials: MT
authors.lastname: Barrack
authors.forename: Ashraf
authors.initials: A
authors.lastname: Abdelkerim
authors.forename: Marci A
authors.initials: MA
authors.lastname: Goolsby
authors.forename: Julie C
authors.initials: JC
authors.lastname: Arends
authors.forename: Leanne L
authors.initials: LL
authors.lastname: Seeger
mesh_terms: D000704:Analysis of Variance; D001842:Bone and Bones / Q000293:injuries*; D003661:Decision Support Techniques; D005260:Female; D005500:Follow-Up Studies; D015775:Fractures, Stress / Q000175:diagnosis* / Q000209:etiology; D006801:Humans; D016014:Linear Models; D008279:Magnetic Resonance Imaging; D008297:Male; D011379:Prognosis; D011446:Prospective Studies; D020127:Recovery of Function; D012307:Risk Factors; D012737:Sex Factors; D013997:Time Factors; D014142:Track and Field / Q000293:injuries*; D015599:Trauma Severity Indices; D055815:Young Adult
keywords: MRI grading; bone stress injury; female athlete triad; stress fracture